This invention relates to a method of preparing a green composition containing hydraulic substance and a method of utilizing the same.
In the preparation of green mortar or green concrete containing a powder of hydraulic substance and water containing sand, even when the percentage of the ingredients is controlled such that concentration of a cement paste utilized will have the same water to cement ratio the quality of the product is not always the same. The present invention relates to a method by which the surface of a fine aggregate is covered with a stable coating of a hydraulic substance so as to obtain a green composition free from any segregation, bleeding and precipitation of the aggregate, thus obtaining concrete products having uniform mechanical strength and stability. According to the method of this invention even when the concentration of the composition is small, the hydration reaction takes place under a state in which coated or shelled sand particles having a small water to cement ratio are in a continuously contacted state, such state binding the portion of the composition having a large water to cement ratio thus manifesting a high mechanical strength which allows for the manufacture of various concrete products having high dimensional accuracies.
Products prepared by using such hydraulic substances as cement and plaster, are widely used in various civil works, and for constructing buildings or the like and efforts have been continuously made for improving the method of incorporation and mixing the ingredients of green concrete or green mortar and to develop new additives as dispersing agents and improved cement. Despite such numerous researches and experiments there still remains a number of problems to be solved so it has been difficult to obtain products of stable quality. Especially, the solution of the problems of segregation, bleeding and precipitation which occur after sand particles have been coated with a hydraulic substance is the most important, so that samples for measuring the mechanical strength were obtained after removing portions in which bleeding or precipitation has occurred. In the past, it was assumed that the concentration of a green paste prepared by admixing such ingredients as water, a powder of cement, a fine aggregate as sand, a coarse aggregate and various dispersing agents was constant. In other words, it has been considered that the products utilizing the identical aggregates, and the same water to cement ratio would have the same strength. In a method utilizing a high grade dehydration agent, a mass of cement was dispersed with a dieta potential, but in this method, consideration was not made for the variation in the concentration of the paste utilizing water containing sand, as above described.